linux-kernel - Re: [PATCH v3 1/3] acpi : cpu hot-remove returns error when cpu

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Date:	Thu, 12 Jul 2012 10:48:07 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	lenb@...nel.org, srivatsa.bhat@...ux.vnet.ibm.com
Subject: Re: [PATCH v3 1/3] acpi : cpu hot-remove returns error when
 cpu_down() fails

On Thu, 2012-07-12 at 20:22 +0900, Yasuaki Ishimatsu wrote:
> Even if cpu_down() fails, acpi_processor_remove() continues to remove the cpu.
> But in this case, it should return error number since some process may run on
> the cpu. If the cpu has a running process and the cpu is turned the power off,
> the system may not work well.
> 
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> 
> ---
>  drivers/acpi/processor_driver.c |   18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
> 
> Index: linux-3.5-rc4/drivers/acpi/processor_driver.c
> ===================================================================
> --- linux-3.5-rc4.orig/drivers/acpi/processor_driver.c	2012-06-25 04:53:04.000000000 +0900
> +++ linux-3.5-rc4/drivers/acpi/processor_driver.c	2012-07-05 21:02:58.711285382 +0900
> @@ -610,7 +610,7 @@ err_free_pr:
>  static int acpi_processor_remove(struct acpi_device *device, int type)
>  {
>  	struct acpi_processor *pr = NULL;
> -
> +	int ret;
> 
>  	if (!device || !acpi_driver_data(device))
>  		return -EINVAL;
> @@ -621,8 +621,9 @@ static int acpi_processor_remove(struct
>  		goto free;
> 
>  	if (type == ACPI_BUS_REMOVAL_EJECT) {
> -		if (acpi_processor_handle_eject(pr))
> -			return -EINVAL;
> +		ret = acpi_processor_handle_eject(pr);
> +		if (ret)
> +			return ret;
>  	}
> 
>  	acpi_processor_power_exit(pr, device);
> @@ -841,12 +842,17 @@ static acpi_status acpi_processor_hotadd
> 
>  static int acpi_processor_handle_eject(struct acpi_processor *pr)
>  {
> -	if (cpu_online(pr->id))
> -		cpu_down(pr->id);
> +	int ret;
> +
> +	if (cpu_online(pr->id)) {
> +		ret = cpu_down(pr->id);
> +		if (ret)
> +			return ret;
> +	}
> 
>  	arch_unregister_cpu(pr->id);
>  	acpi_unmap_lsapic(pr->id);
> -	return (0);
> +	return ret;

ret is uninitialized when !cpu_online().

Thanks,
-Toshi

>  }
>  #else
>  static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
> 
> --
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